This proposal intends to optimize catheter-based micro radio frequency antennas used in MR-guided, intravascular interventions for high resolution imaging of the arterial wall. A resolution of approximately 200 microns is needed to depict atherosclerotic plaque components in a diseased vessel wall. RF antennas must provide a high signal-to-noise ratio (SNR) to keep acquisition time (TA) short during interventions. Our previous work showed that simple changes in coil winding patterns can double SNR and reduce TA by 4. Thus, we focus on an in-depth optimization of catheter-coils with respect to their SNR. For this purpose, an extensive computer simulation program will be developed which calculates 3D-SNR maps as a function of the antenna geometry and orientation relative to BO. In order to find the best antenna design for a given application, this software will be specifically used to: 1) perform a formal comparison of common intravascular coils (e.g. loop vs. opposed solenoid coil), and 2) investigate possible improvements in SNR by changing geometry through hybrid combination of multiple designs (e.g. by adding loops to an opposed solenoid coil). Design changes necessitate recalculation of the SNR map. When comparing different coils, the best design will be chosen based on the highest SNR calculated at the anticipated location of the wall in a cross-sectional slice through vessel and center of the coil. We will restrict our optimization to coils for coronary and renal artery imaging and construct potentially useful designs identified by simulations using surface mount or micro fabrication technology. All assembled devices will be tested in MR phantom imaging. SNR maps will be acquired at multiple orientations. Measured SNR maps will be compared with simulation data and simulation accuracy for all coils manufactured will be evaluated. Finally, the best designs will be tested in vivo in a porcine animal model. We anticipate that this project will lead to identification and prototyping of SNR-optimized catheter coils for further testing in animal models of vascular disease in Phase II.